1. Field of the Invention
This invention concerns a coupling device and arrangement used to couple or attach a backhoe frame to the main frame of a host tractor. More specifically, a wedge block, slidably carried between selected tractor frame members and a backhoe mounting collar of the backhoe, is urged between the backhoe mounting collar and the tractor main frame. As the wedge block is urged into position any play or looseness between the main frame and the backhoe frame is taken up such that the backhoe frame is securely mounted to the main frame and relative motion between these parts is eliminated.
2. Description of the Prior Art
Wedge locking devices have been used in a multitude of applications where it has been necessary to securely lock two components together while maintaining a certain ease of disassembly. Typical known uses of wedge locking devices include: devices for attaching tractor wheels to agricultural tractor axles, construction equipment loader hinge pin retainers and, safety frame attaching devices as well as many other applications.
Quick attach coupling arrangements are also well known in the construction equipment industry. In general these quick attach devices include parts to accomplish attachment in two stages. The first equipment requirement of a quick attach device is some type of an alignment system where the attachment may be positioned on the host vehicle in a preliminary and somewhat loose association. The second stage in attaching an implement or accessory attachment is to positively lock the attachment to the host implement. This is often accomplished through the actuation of a pin type latching bolt that may be spring loaded or hydraulically actuated into a receiving alignment aperture.
Backhoes, generally excavating scoops or shovels mounted for articulated motion to the back end of a host vehicle, have been known to be removably mounted to the host vehicle. A host vehicle may typically be a crawler tractor that may also have a front mounted loader bucket or the host vehicle may be an industrial tractor of the wheeled variety having a front mounted loader bucket. The advantages gained by providing provisions for removing the backhoe when it is not needed include increased maneuverability of the host vehicle, reduced ground pressure exerted by the host vehicle and interchangability of the backhoe between a plurality of host vehicles.
The closest prior art known to the Applicant is the current production removable backhoe manufactured by the International Harvester Company. The model designation of this removable backhoe is the 3142A Quick Attach Backhoe. This prior art backhoe mounting arrangement includes a mounting plate secured to the host vehicle. The backhoe proper includes a frame incorporating a pair of vertical cavities that are open at the end of the backhoe frame that faces the mounting plate carried by the host vehicle. A pair of stationary pins traverse the lower sections of the vertical cavities, while a pair of removable pins may be inserted through upper apertures in the side plates that proscribe boundaries of the vertical cavities.
The mounting plate, which is attached to the host vehicle's frame, also includes a projecting pair of vertically disposed carrier members each having hook-like projections on the bottom section of the carrier members and apertures on the top section of the carrier members.
The backhoe is mounted to the host vehicle when the bottom hooks cradle the stationary pins in the lower sections of the vertical cavities of the backhoe frame and the removable pins are inserted through the apertures at the top of the carrier members and the respective upper apertures in the side plates of the vertical cavities.
Once the top pins are inserted the backhoe is secure to the host vehicle. However, due to necessary tolerances between the upper pins and the pin receiving holes, the backhoe may be slightly movable relative to the host vehicle. As the pins and the accommodating apertures wear the "tightness" between the backhoe and the host vehicle will deteriorate. This imprecise fit may not affect the operation of the backhoe but it is less than optimal and may impose unnecessary stresses on the backhoe frame or the host vehicle frame.
Another disadvantage of prior art backhoe mounting arrangements is that when the assembly is new it may be difficult to insert or remove the upper mounting pins due to the relatively close tolerances between the pins and receiving apertures. Of course as these parts wear and become deformed ease of assembly may improve unless the pins are deformed which may cause disassembly difficulties.